Underwater pipeline-burying apparatus

ABSTRACT

The apparatus includes a framework of tubular members adapted to straddle the pipeline to be buried and to be supported thereon for movement along the pipeline. High-pressure jets of water directed ahead of the framework wash away the bottom below the pipeline and form a trench into which the pipeline can fall. High-pressure jets of water directed rearwardly of the framework move the framework along the pipeline. The volume of water flowing to the propulsion jets is controlled, preferably, by a diver riding the framework to control the speed at which the framework is propelled along the pipeline, as dictated by the rate the bottom sediments and silt are removed from beneath the pipeline ahead of the framework.

United States Patent 3,368,358 2/1968 Elliott 3,401,473 9/1968 Schrom ABSTRACT: The apparatus includes a framework of tubular members adapted to straddle the pipeline to be buried and to be supported thereon for movement along the pipeline. Highpressure jets of water directed ahead! of the framework wash away the bottom below the pipeline and form a trench into which the pipeline can fall. High-pressure jets of water directed rearwardly of the framework move the framework along the pipeline. The volume of water flowing to the propulsion jets is controlled, preferably, by a diver riding the framework to control the speed at which the framework is propelled along the pipeline, as dictated by the rate the bottom sediments and silt are removed from beneath the pipeline ahead of the framework.

PATENTED APR27|971 3578,111

SHEET 1 OF 3 URBAN A. HENRY, Jl'.

Qww Q Dw ATTORNEYS mm mm 3.

PATENTEU 1111271911 SHEET 2 [IF 3 URBAN 14. HENRY, Jr.

I NVEN 1 ()R 92 0mm fiw gm mm 1 O t 1 mw fl A A 1 mm mm T g? a V ,Ulifl mm N A "5 PR ATTORNEYS PATENTED APR 27 1911 SHEET 3 0F 3 FIG. 7

URBAN A. HENRKJr.

INVENTOR A T TORNE YS 3,576,l ll

UNDERWATER PllPElLllNE-BURYHNG APPARATUS This invention relates to apparatus for burying pipelines and in particular to apparatus for burying pipelines laying on the bottom of a body of water.

High-pressure water jets alone on in combination with endless chain carrying earth-removing buckets are commonly used for excavating a trench below underwater pipelines into which the line can fall. Usually, no effort is made to cover the line after it has fallen into the trench, this being left to the natural tendency of the water to level out the bottom. In other words, usually the currents existing in the body of water will wash sand and silt on top of the pipe after it has sunk to the bottom of the trench and cover it up in a reasonably short period of time.

The framework, upon which the hydraulic jets or bucket diggers are mounted, is usually pulled along the pipeline by a surface vessel or by a winch mounted on a surface vessel which is anchored ahead of the framework over the pipeline. The rate at which the bottom silt and sediment is washed away and removed from beneath the pipeline varies and therefore the rate at which the framework should be pulled along the pipeline varies. When pulling such apparatus from the surface of the water it is difficult to know whether or not you are pulling it as fast as it should be pulled or too fast for the particular bottom conditions it is encountering.

It is an object of this invention to provide underwater pipeline-burying apparatus that is self-propelled.

lt is another object of this invention to provide underwater pipeline-laying apparatus that propels itself along a pipeline at a speed that is adjusted by the rate at which the bottom silt and sediment is removed from beneath the pipeline ahead of the apparatus.

It is yet another object of this invention to provide underwater pipeline-laying apparatus wherein the speed at which the apparatus moves along the pipeline can be controlled by a diver riding the apparatus and observing the rate at which the bottom silt and sediment is being removed ahead of the apparatus.

It is yet another object of this invention to provide an underwater pipeline-laying apparatus that is propelled along the pipeline by the reactive forces produced by rearwardly discharging hydraulic nozzles thereby providing a propelling force for the apparatus that will readily yield should, for some reason, the apparatus be stopped or slowed in its forward progress without causing any permanent damage to the apparatus.

Underwater pipelines may not extend along the bottom of the water in a straight line. Long pipelines and pipelines of relatively small diameter may curve back and forth several times across their intended direction of travel. ln bodies of water having a strong crosscurrent, a pipeline will tend to curve in the direction of the current.

It is another important feature and object of this invention to provide underwater pipeline-laying apparatus that can change its direction of travel and be guided along a curved pipeline by a diver.

These and other objects, advantages, and features of the invention will be apparent to those skilled in the art from a consideration of this application, including the attached drawings and appended claims.

In the drawings:

FIG. I is a plan view of one embodiment of the apparatus of this invention in operation burying an underwater pipeline along with the surface vessel and apparatus employed to support the underwater operation;

FIG. 2 is a side view of the apparatus shown in FIG. 1;

H6. 3 is a top plan view, on an enlarged scale from that of H08. 1 and 2, of the underwater pipeline-burying apparatus of FIGS. land 2;

FIG. 4 is a side view ofthe apparatus of FIG. 3;

FIG. 5 is an end view ofthe apparatus of FIGS. 3 and 4;

FIG. 6 is a plan view of an alternate embodiment of the apparatus ofthis invention;

FIG. 7 is a side view of the apparatus of FIG. 6; and

FIG. 8 is a front view ofthe apparatus of FIG. 6.

Referring first to FIGS. 3, 4 and 5, the apparatus includes frame means, generally indicated by the number 10, adapted to move along pipeline lll. In the embodiment shown, the frame means includes means for engaging the pipeline to support the frame means on the pipeline for movement therealong. Such means in the embodiment shown includes rollers 12 and 13.

Frame means 10 comprises a framework of tubular members. The first pair 14a and 14b of tubular members are located on opposite sides of pipeline ill and parallel thereto. These tubular members are generally horizontal and are located below the pipeline adjacent the bottom of the trench formed by the second pair of tubular members to be described below. Each of tubular members 14a and 14b is provided with a plurality of jets or nozzled 15, which are spaced longitudinally along the tubular members. These jets are positioned so that high-pressure fluid inside of tubular members 14a and 14b can flow from the inside of the tubular members through the nozzles in an upward and rearward direction, rearward being to the left as theapparatus is viewed in the drawings. The reactive component of the rearwardly directed high velocity jets of fluid through nozzles 15 tends to urge frame means 10 along the pipeline to the right, as viewed in the drawings. The jets are directed somewhat upwardly to also give an additional cleaning action to remove any bottom silt or sediment that is not removed by the trench-forming means located at the front of the frame means.

The trench-forming means in the embodiment shown comprises a second pair of tubular members, 17a and 1712. These two tubular members are parallel to each other and they are located on opposite sides of pipeline 11. Their lower ends are connected to the forward ends of tubular members 14a and 14b and they extend upwardly therefrom at an angle to the vertical. Each tubular member is provided with a plurality of longitudinally spaced nozzles 18. These nozzles are positioned to direct streams of pressure fluid from the inside of tubular members 17a and 17b in a forward direction, i.e., to the right as the apparatus is viewed in the drawings. It is the purpose of these forwardly directed streams offluid to wash away the bottom sediments and silt located below pipeline 11 ahead of the framework.

In the embodiment shown, a third pair of tubular members 20a and 20b extend along the bottom side ofa portion of tubular members 14a and 1412. This third pair of tubular members is provided with side openings 21 through which fluid inside tubular members 2011 and 20b can escape. Preferably, these members are provided with air under pressure whereas the first and second pair of tubular members are provided with water under pressure. The action of the air flowing upwardly from below tubular members 14a and 14b aerates the water thereabove and improves the cleaning action of the high velocity water jets emitted by nozzles 1.5.

As stated above, the high-pressure water is preferably employed for eroding the bottom sediments through nozzles 18 and for providing the propulsion to the framework through nozzles 15. Water is supplied to tubular members 14a and 1412 through upwardly extending water supply conduits 22a and 2212, respectively. Tubular members 17a and 17b are supplied with water through conduits 23a and 2312, respectively. Water supply conduits 22a and 23a are connected together at their upper ends and both are supplied with water from flexible hose 24a. in the same manner, water supply conduits 22b and 23b are connected together at their upper ends and in turn to water hose 24b. cross brace 25 extends between the two pairs of connected water supply conduits to hold them and in turn the pairs of tubular members 14a and Mb, and 17a and 17!) the proper distance apart. Roller 12 is located below cross brace 25 and is supported at its ends by downwardly extending brackets 26, only one of which can be seen in the drawings. Shaft 12a and suitable bearings (not shown) are provided to permit roller 12 to roll along pipeline ll and support the forward end of frame means 10. Brace 26 between the upper ends oftubular members and 17b provide additional stiffness to the framework.

Tubular members 20a and 20b are provided with air by inverted Ueshaped member 27 and air hose 28, which extends to the surface. Brackets 29a and 29b are attached to opposite legs of U-shaped tubular member 27 to support roller 13 through shaft 13a and suitable bearings (not shown). Roller 13 supports the rearward end of frame means for movement along the pipeline.

Preferably, means are provided to control the flow of highpressure fluid, such as water, to the first pair of tubular members to thereby control the speed that thrust nozzles 15 propel the framework along pipeline II. In the embodiment shown, valves 30a and 30b are located in water conduits 22a and 2212 respectively for this purpose. The control of the amount of water going to thrusters 15 is located on the framework because it is contemplated that a diver will ride the framework as it moves along the pipeline to observe the rate that the trench is being dug below the pipeline and to control the speed of the apparatus accordingly.

The preferred manner of operation of the apparatus is shown in FIGS. 1 and 2. Frame means 10 is lowered into position astride pipeline lll. Initially, of course, a diver may need to excavate below the line with jets to form a cavity large enough to permit the framework to straddle the pipeline. Water hoses 24a and 24b and air hose 28 extend upwardly to a surface vessel, shown in the drawings as barge 32, where they are connected to sources of high-pressure water and highpressure air, such as pumps 33 and compressor 35 positioned on barge 32. Float 34 supports the hoses and keeps them from falling down around the framework of the apparatus and interfering with its operation.

Diver 36, when operations are started, will ride astridc pipeline 11 supported by tubular members 14a and 1411 so that he can conveniently operate the levers of control valves 30a and 30b. This places the diver in position to observe the opera tion of the forwardly directed jets emitted through nozzles 18 and to control the speed of the apparatus along the pipeline accordingly. Since the water to cutting nozzles 18 and thrusting nozzles 15 comes from a common source, when the apparatus strikes or encounters a section of bottom silt and sediment which is easily removed and quickly washed away by the jets from cutting nozzles 18, the speed of the apparatus can be increased by opening valves 30a and 30b. This will have an effect of reducing the output of water through cutting nozzles 18 and thereby reduce the rate at which the formation is being removed. This would means that as the speed is brought up, the rate of removal of material is reduced and therefore the two can be brought into balance more quickly. Conversely, if a section of bottom sediment and silt is encountered which is difficult to wash away, the diver will slow down the forward progress of the apparatus by closing off valves 30a and 301). This will increase the amount of water being emitted through cutting nozzles 18, which is desirable, since this will increase the ability of nozzles I8 to cut away these sections of more consolidated bottom silt and sediment.

Enough water will have to be admitted through thrusters 15, of course, to overcome the reactive force produced by cutting nozzles 18. This can be controlled by the diver so that he moves forward and keeps cutting nozzles 18 the proper distance away from the formation being eroded away. In the same way, he can close down on the valves a and 20b and allow the cutting nozzles 18 to move him rearwardly should for any reason he want to back up.

By dividing the flow between the nightand left-hand side of the tubular members making up the framework, the diver can also guide the apparatus to some extent and thereby maintain the rollers in proper position on the pipeline, even if the pipeline is curved to some extent. He can also cause the framework to fishtail as it moves down the pipeline to provide an eroding action that will tend to widen trench 40. This may be desirable in certain instances.

The ends of tubular members 14a, 14b, and 17a and 17b are connected to valves 38 having a large opening. Should any debris enter one ofthe tubular members and interfere with the flow of fluid through it, the appropriate valve 38 can be opened to permit the pressure fluid to wash the debris out of the tubular member.

An alternate embodiment of the apparatus of this invention is shown in FIGS. 68 of the drawings. This apparatus includes frame means, generally indicated by the number 39, adapted to moved along pipeline 11. The frame means in this embodiment includes a first pair of L-shaped tubular members, which are located on opposite sides of pipeline 11 with legs 41a and 42a of the tube members extending generally parallel to the pipeline. Legs 41a and 4211 are generally horizontal and are located below the pipeline adjacent the bottom of the trench formed by the trench-forming means to be described below.

Legs 41b and 42b of the first pair of tubular members extend generally vertically along each side of pipeline 11 and are in parallel, spaced, relationship with each other. A plurality of jets or nozzles 43 are spaced longitudinally along most of legs 41a and 42a and upwardly along a portion oflegs 41b and 42b. These nozzles, like nozzles 15 in the first embodiment, are positioned so that high-pressure fluid can flow from the inside of the tubular members 41 and 42 through the nozzles in an upward and rearward direction, rearward being to the right as the apparatus is viewed in FIGS. 68. The reactive component of the rearwardly directed high velocity jets of fluid through nozzles 43 tends to urge frame means 40 along the pipeline to the left. The jets are directed somewhat upwardly to give an additional cleaning action for moving any bottom silt or sediment that may have been washed into a position above them by the cleaning action of the trench-forming means located at the front ofthe frame.

In this embodiment, the trench-forming means comprises a second pair of tubular members 44 and 45. These tubular members are generally U-shaped and are located on opposite sides of pipeline 11. Legs 44a and 45a form the forwardmost part of the frame and extend upwardly in spaced parallel relationship from well below pipeline 11 to an elevation somewhat above the pipeline. Each leg 44a and 45a has a plurality of Iongitudinally spaced nozzles 46 mounted thereon. These nozzles are positioned to direct streams of pressure fluid from the inside of legs 44a and 45a in a forward direction, i.e., to the left as the apparatus is viewed in the drawings. It is the purpose of these forwardly directed streams of fluid, usually water, to wash away the bottom sediments and silt located below and to the sides of pipeline 11 ahead of the frame and form a trench into which the pipeline can sink below the surface of the bottom of the water.

Legs 44b and 45b of the U-shaped second pair of tubular members that make up part of frame 40 extend generally vertically from the lower end of legs 44a and 45a in parallel, spaced relationship on opposite sides ofpipeline l 1.

A third pair of tubular members 47 and 48 direct streams of air into the water adjacent the bottom of the trench formed by the trench-forming means of the apparatus. These tubular members are also L-shaped having legs 47a and 48a extending generally parallel to pipeline 11 and also parallel to and extending along the bottom of legs 41a and 42a of the first pair of L-shaped tubular members. Legs 47b and 48b are generally vertical and parallel.

Means are provided to engage pipeline 11 and support the apparatus for movement therealong. In this embodiment, mounting plates are attached to legs 44b and 45b, as shown, to support roller 50 therebetween. This roller engages pipeline l1 and supports the forward end of the apparatus. Mounting plates 51 are attached to legs 47b and 48b and support rollers 52 to engage the pipeline and support the rearward end of the apparatus. Each mounting plate has a plurality of mounting holes to permit the rollers to be moved up and down with respect to the plates. As shown, roller 50 is located in the uppermost mounting holes; this produces the deepest trench. Roller 52 is located in one of the roller mounting holes below the top since the pipeline may tend to be lower at this point since it is falling into the ditch at this point. By lowering roller 52 this allows the apparatus to remain substantially horizontal as it moves along the pipeline. [f the pipeline is relatively stiff, roller 52 may well need to be positioned in the top mounting holes to keep the apparatus substantially horizontal or level. For more shallow trenches, of course, the rollers can be located in the lower mounting holes.

The upper ends of the vertical legs of each of the three pairs of tubular members are connected together by horizontal conduits or tubular members 54, 55, and 56, respectively. T- shapped fittings are located in the middle of each of conduits 5 1-56 for connecting each pair of tubular members to flexible hoses 58, 59 and 60, respectively. Valves 6] and 62 control the flow of fluid through hoses 58 and 59, respectively. In this manner, a diver riding the apparatus can adjust valve 61 to control the speed at which the apparatus moves along the line and by adjusting valve 62 he can control the cutting action of the forwardly directed jets produced by nozzles 46. No diveroperated control is provided for the flow of air to legs 47a and 480 which, by the way, are provided with openings through which the air can escape. This can be controlled from the surface. A diver-operated valve could be provided if desired. Also, if more buoyancy is desired, buoyancy tanks could be attached to the apparatus and the amount of air in them adjusted by the diver to control the buoyancy of the apparatus. Generally, it is desirable for the apparatus to have negative buoyancy sufficient for it to rest with some force on pipeline ll. ln this way, it does not have to be tied down in any way.

I The reaction from the jets produced by nozzles 43 and 46, of

course, will tend to hold the apparatus down.

In this embodiment, means are provided to pivotally connect the first pair of tubular members with the second pair of tubular members and means are provided to pivot one relative to the other to permit a diver to change the direction of travel of the apparatus along the pipeline.

In this embodiment the hinge means includes hinge pin 64, which extends through holes in plates 65 attached to both horizontal members 54 and 55 and portions of tees 54a and 55a. To pivot the trench-forming means relative to the propulsion means, jackscrew 67 is provided. To keep the drawing simple, the jackscrew is shown in FIG. 6, only. The jackscrew includes a parallelogram-type linkage connected between the two pairs of tubular members adjacent the top of legs 44b and 41b as shown. The shape of the parallelogram can be changed by threaded rod or screw 68 to move the legs 44b and 41b apart or together as the case may be. Handle 67a is provided to permit the diver to rotate screw 68 easily. By changing the angle the forwardly directed jet streams make with the direction of the jets from the propulsion nozzles, the apparatus can more easily follow the curvature ofa pipeline.

This embodiment is operated in the same manner as the first-described embodiment being supplied with water and air under pressure from the surface.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus and structure.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matters herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. Underwater pipeline-burying apparatus comprising frame means adapted to move along the pipeline, rearwardly directed jet means through which fluid under pressure can be discharged into the ambient water to provide a reactive force that is sufficient to move the frame means forwardly along the pipeline, means carried by the frame means for excavating below the pipeline ahead of the frame means as it is moved along the pipeline by the rearwardly directed jet means, said frame means including two portions with the jet means located on one portion and the excavating means on the other, means pivotally connecting the two portions, and means for pivoting one portion relative to the other as the frame means move along the pipeline.

2. The underwater pipe-burying apparatus of claim 1 in which the means for pivoting comprises means carried by the frame means for engaging the pipeline to guide the frame means along the pipeline as the frame means is moved therealong by the rearwardly directed jet means.

3. The underwater pipeline-burying apparatus of claim 1 in which the excavating means comprises second jet means through which fluid under pressure can be discharged to wash the bottom slit and sediments from under-the pipeline ahead ofthe frame means.

4. The apparatus of claim 3 further provided with means for controlling the flow of pressure fluid to the first jet means to control the speed the frame means moves along the pipeline.

5. The apparatus of claim 4, in which the frame means includes a first pair of horizontal tubular members in spaced parallel relationship with each other and with said pipeline, and in which said rearwardly directed jet means includes a plurality of nozzles attached to said tubular members through which fluid under pressure may be discharged from the interior of said tubular members, said members being positioned on opposite sides and below the pipeline with their attached nozzles being positioned to direct the fluid flowing therethrough both upwardly and in a direction opposite to the desired direction of travel of the frame means along the pipeline to provide said reactive force to move the frame means in the desired direction and to wash bottom silt and sediments from under the pipeline as the frame moves therealong.

6. Underwater pipeline-burying apparatus comprising frame means adapted to move along the pipeline, rearwardly directed jet means through which fluid under pressure can be discharged into the ambient water to provide a reactive force that is sufficient to move the frame means forwardly along the pipeline, means for controlling the flow of pressure fluid to the first jet means to control the speed of the frame means moves along the pipeline, means carried by the frame means for excavating below the pipeline ahead of the frame means as it is moved along the pipeline by the rearwardly directed jet means, said excavating means comprising second jet means through which fluid under pressure can be discharged to wash the bottom silt and sediments from under the pipeline ahead of the frame means, said frame means further including a first pair of horizontal tubular members in spaced parallel relationship with each other and with said pipeline and in which said rearwardly directed jet means includes a plurality of nozzles attached to said tubular members through which fluid under pressure may be discharged from the interior of said tubular members, said members being positioned on opposite sides and below the pipeline with the attached nozzles being positioned to direct the fluid flowing therethrough both upwardly and in the direction opposite to the desired direction of travel of the frame means along the pipeline to provide said reactive force to move the frame means in the desired direction and to wash bottom silt and sediments from under the pipeline as the frame moves therealong, and a second pair of spaced parallel tubular members with each having a plurality of nozzles attached thereto through which fluid under pressure may be discharged from the interior of said tubular members, said second pair of tubular members being positioned to extend upwardly from the forward ends of the first pair of tubular members on opposite sides of the pipeline with the nozzles positioned to direct the fluid flowing therethrough in the general direction of travel ofthe frame means to wash the bottom silt and sediments from under the pipeline ahead of the frame means.

7. The apparatus of claim 6 in which the frame means further includes a third pair of tubular members, each of which is adjacent and parallel to one of the first pair of tubular members, said third pair of members having a plurality of holes spaced along their upper surface through which air may flow from the interior thereof to aerate the water thereabove to aid the apparatus in removing bottom silt and sediments from below the pipeline.

8. The apparatus of claim 6 in which said frame means in cludes spaced horizontal rollers mounted to rotate around axes transverse the longitudinal axis of the pipeline for supporting the first and second pairs of tubular members on opposite sides of the pipeline and for movement therealong.

9. The apparatus ofclaim 6 further provided with means for connecting the first pair of tubular members to a source of fluid under pressure, said means including valve means for operation by a diver riding said frame means to control the volume of fluid flowing to said first set of tubular members to control the speed to the frame means along the pipeline.

10. The apparatus of claim 9 in which said means for connecting the first tubular means to a source of pressure fluid also connects the second tubular means to the same source of pressure fluid and the manipulation of the valve means to control the volume of fluid flowing to the first tubular members affects the volume flowing to the second set of tubular members.

11. Apparatus for burying a pipeline lying on the bottom of a body of water, comprising frame means adapted to be supported by the pipeline to be buried including means for engaging the pipeline to support the frame means for movement along the pipeline, and to guide the frame means along the pipeline, a first set of rearwardly directed propulsion nozzles carried by the frame means to provide the total force required for moving the frame means forward along the pipeline, a second set of cutting nozzles carried by the frame means to discharge generally in the direction of travel of the frame means for washing the bottom from under the pipeline ahead of the frame means to permit the pipeline to sink below the level of the bottom after the frame means has moved on, and means for varying the flow of fluid to the first sets of nozzles to control the speed to the frame means along the pipeline.

12. The apparatus of claim 11 in which the frame means straddles the pipeline and said support means includes rollers to engage the pipeline for supporting the frame for movement therealong.

13. The apparatus of claim 11 in which the propulsion nozzles are carried by a first portion of the frame means, the cutting nozzles are carried by a second portion of the frame means, and the apparatus is further provided with means pivotally connecting the first and second portions of the frame means and means for pivoting one portion relative to the other to change the direction of travel of the apparatus along a pipeline.

14. The apparatus of claim 13 further provided with means for connecting the propulsion nozzles and the cutting nozzles to a source offluid under pressure and valve means for changing the rate offlow of pressure fluid to said nozzles.

15. Underwater pipe-burying apparatus comprising a framework of tubular members adapted to be supported by the pipeline to be buried and for movement therealong, said framework including a first pair of horizontal tubular members located below and on opposite sides of the pipeline and parallel thereto with each of the members having a plurality of nozzles spaced longitudinally therealong through which water can flow from the interior of the tubular members upwardly or rearwardly of the framework to provide a reactive force for urging the framework along the pipeline and to wash bottom sediment from under the pipeline, a second pair of upwardly inclined parallel tubular members located on opposite sides of the pipeline, each of said tubular members having a plurality of nozzles spaced longitudinally therealong through which water can flow from the interior of the second pair of tubular members generally in the direction of travel of the framework to wash away the bottom sediments ahead of the framework and below the pipeline, means for supplying the first and second pairs of tubular members with water under pressure, and means carried by the framework and operable by a diver riding the framework for controlling the flow of water to the first pair of tubular members to control the speed that the framework moves along the pipeline.

16. The apparatus of claim 15 further provided with means pivotally connecting the first and second pairs of tubular members and means for pivoting the first relative to the second to change the direction of travel of the apparatus.

17. Apparatus for excavating a ditch under a pipeline lying on the bottom of a body of water comprising a U-shaped frame for straddling the pipeline, means carried by the frame to engage the pipeline and cause the frame to follow the pipeline as the frame moves forwardly, a plurality of forwardly directed nozzles carried by the frame through which pressure fluid from the surface is discharged to erode away the bottom below the pipeline to form a ditch into which the pipeline can fall, and rearwardly directed nozzle means through which pressure fluid is discharged to provide the total force required for moving the frame forwardly along the pipeline as the fluid discharged from the forwardly directed jets erodes the bottom from under the pipeline, and means controlling the flow of fluid to said forwardly and rearwardly directed jets so that the forward speed of the apparatus can be varied independently of the flow offluid to the forwardly directed jets.

18. The apparatus ofclaim 17 in which the frame includes a forward U-shaped section and a rearward U-shaped section and hinge means connecting the forward and rearward sections together to allow the frame to more easily follow the pipeline.

19 Apparatus for excavating a ditch under a pipeline lying on the bottom of a body of water comprising, first and second U-shaped frame means for straddling the pipeline in tandem, hinge means connecting the first and second frame means for relative movement around a vertical axis to permit the frame means to more easily travel around curves in the pipeline, forwardly directed fluid jet means carried by the first frame means through which a fluid jet can be directed ahead of the frame means to excavate a ditch under the pipeline, and rearwardly directed fluid jet means through which a fluid jet can be directed rearwardly to provide a sufficient reactive force to move the frame means forwardly along the pipeline as the forwardly directed fluid jet means excavates the ditch under the pipeline.

20. The apparatus of claim 19 further provided with means for directing a gas, such as air, into the ditch formed by the forwardly directed jet means to help clean the ditch for the pipeline. 

1. Underwater pipeline-burying apparatus comprising frame means adapted to move along the pipeline, rearwardly directed jet means through which fluid under pressure can be discharged into the ambient water to provide a reactive force that is sufficient to move the frame means forwardly along the pipeline, means carried by the frame means for excavating below the pipeline ahead of the frame means as it is moved along the pipeline by the rearwardly directed jet means, said frame means including two portions with the jet means located on one portion and the excavating means on the other, means pivotally connecting the two portions, and means for pivoting one portion relative to the other as the frame means move along the pipeline.
 2. The underwater pipe-burying apparatus of claim 1 in which the means for pivoting comprises means carried by the frame means for engaging the pipeline to guide the frame means along the pipeline as the frame means is moved therealong by the rearwardly directed jet means.
 3. The underwater pipeline-burying apparatus of claim 1 in which the excavating means comprises second jet means through which fluid under pressure can be discharged to wash the bottom slit and sediments from under the pipeline ahead of the frame means.
 4. The apparatus of claim 3 further provided with means for controlling the flow of pressure fluid to the first jet means to control the speed the frame means moves along the pipeline.
 5. The apparatus of claim 4, in which the frame means inCludes a first pair of horizontal tubular members in spaced parallel relationship with each other and with said pipeline, and in which said rearwardly directed jet means includes a plurality of nozzles attached to said tubular members through which fluid under pressure may be discharged from the interior of said tubular members, said members being positioned on opposite sides and below the pipeline with their attached nozzles being positioned to direct the fluid flowing therethrough both upwardly and in a direction opposite to the desired direction of travel of the frame means along the pipeline to provide said reactive force to move the frame means in the desired direction and to wash bottom silt and sediments from under the pipeline as the frame moves therealong.
 6. Underwater pipeline-burying apparatus comprising frame means adapted to move along the pipeline, rearwardly directed jet means through which fluid under pressure can be discharged into the ambient water to provide a reactive force that is sufficient to move the frame means forwardly along the pipeline, means for controlling the flow of pressure fluid to the first jet means to control the speed of the frame means moves along the pipeline, means carried by the frame means for excavating below the pipeline ahead of the frame means as it is moved along the pipeline by the rearwardly directed jet means, said excavating means comprising second jet means through which fluid under pressure can be discharged to wash the bottom silt and sediments from under the pipeline ahead of the frame means, said frame means further including a first pair of horizontal tubular members in spaced parallel relationship with each other and with said pipeline and in which said rearwardly directed jet means includes a plurality of nozzles attached to said tubular members through which fluid under pressure may be discharged from the interior of said tubular members, said members being positioned on opposite sides and below the pipeline with the attached nozzles being positioned to direct the fluid flowing therethrough both upwardly and in the direction opposite to the desired direction of travel of the frame means along the pipeline to provide said reactive force to move the frame means in the desired direction and to wash bottom silt and sediments from under the pipeline as the frame moves therealong, and a second pair of spaced parallel tubular members with each having a plurality of nozzles attached thereto through which fluid under pressure may be discharged from the interior of said tubular members, said second pair of tubular members being positioned to extend upwardly from the forward ends of the first pair of tubular members on opposite sides of the pipeline with the nozzles positioned to direct the fluid flowing therethrough in the general direction of travel of the frame means to wash the bottom silt and sediments from under the pipeline ahead of the frame means.
 7. The apparatus of claim 6 in which the frame means further includes a third pair of tubular members, each of which is adjacent and parallel to one of the first pair of tubular members, said third pair of members having a plurality of holes spaced along their upper surface through which air may flow from the interior thereof to aerate the water thereabove to aid the apparatus in removing bottom silt and sediments from below the pipeline.
 8. The apparatus of claim 6 in which said frame means includes spaced horizontal rollers mounted to rotate around axes transverse the longitudinal axis of the pipeline for supporting the first and second pairs of tubular members on opposite sides of the pipeline and for movement therealong.
 9. The apparatus of claim 6 further provided with means for connecting the first pair of tubular members to a source of fluid under pressure, said means including valve means for operation by a diver riding said frame means to control the volume of fluid flowing to said first set of tubular members to control the speed to the frame means aLong the pipeline.
 10. The apparatus of claim 9 in which said means for connecting the first tubular means to a source of pressure fluid also connects the second tubular means to the same source of pressure fluid and the manipulation of the valve means to control the volume of fluid flowing to the first tubular members affects the volume flowing to the second set of tubular members.
 11. Apparatus for burying a pipeline lying on the bottom of a body of water, comprising frame means adapted to be supported by the pipeline to be buried including means for engaging the pipeline to support the frame means for movement along the pipeline, and to guide the frame means along the pipeline, a first set of rearwardly directed propulsion nozzles carried by the frame means to provide the total force required for moving the frame means forward along the pipeline, a second set of cutting nozzles carried by the frame means to discharge generally in the direction of travel of the frame means for washing the bottom from under the pipeline ahead of the frame means to permit the pipeline to sink below the level of the bottom after the frame means has moved on, and means for varying the flow of fluid to the first sets of nozzles to control the speed to the frame means along the pipeline.
 12. The apparatus of claim 11 in which the frame means straddles the pipeline and said support means includes rollers to engage the pipeline for supporting the frame for movement therealong.
 13. The apparatus of claim 11 in which the propulsion nozzles are carried by a first portion of the frame means, the cutting nozzles are carried by a second portion of the frame means, and the apparatus is further provided with means pivotally connecting the first and second portions of the frame means and means for pivoting one portion relative to the other to change the direction of travel of the apparatus along a pipeline.
 14. The apparatus of claim 13 further provided with means for connecting the propulsion nozzles and the cutting nozzles to a source of fluid under pressure and valve means for changing the rate of flow of pressure fluid to said nozzles.
 15. Underwater pipe-burying apparatus comprising a framework of tubular members adapted to be supported by the pipeline to be buried and for movement therealong, said framework including a first pair of horizontal tubular members located below and on opposite sides of the pipeline and parallel thereto with each of the members having a plurality of nozzles spaced longitudinally therealong through which water can flow from the interior of the tubular members upwardly or rearwardly of the framework to provide a reactive force for urging the framework along the pipeline and to wash bottom sediment from under the pipeline, a second pair of upwardly inclined parallel tubular members located on opposite sides of the pipeline, each of said tubular members having a plurality of nozzles spaced longitudinally therealong through which water can flow from the interior of the second pair of tubular members generally in the direction of travel of the framework to wash away the bottom sediments ahead of the framework and below the pipeline, means for supplying the first and second pairs of tubular members with water under pressure, and means carried by the framework and operable by a diver riding the framework for controlling the flow of water to the first pair of tubular members to control the speed that the framework moves along the pipeline.
 16. The apparatus of claim 15 further provided with means pivotally connecting the first and second pairs of tubular members and means for pivoting the first relative to the second to change the direction of travel of the apparatus.
 17. Apparatus for excavating a ditch under a pipeline lying on the bottom of a body of water comprising a U-shaped frame for straddling the pipeline, means carried by the frame to engage the pipeline and cause the frame to follow the pipeline as the frame moves forwardly, a plurality of forwaRdly directed nozzles carried by the frame through which pressure fluid from the surface is discharged to erode away the bottom below the pipeline to form a ditch into which the pipeline can fall, and rearwardly directed nozzle means through which pressure fluid is discharged to provide the total force required for moving the frame forwardly along the pipeline as the fluid discharged from the forwardly directed jets erodes the bottom from under the pipeline, and means controlling the flow of fluid to said forwardly and rearwardly directed jets so that the forward speed of the apparatus can be varied independently of the flow of fluid to the forwardly directed jets.
 18. The apparatus of claim 17 in which the frame includes a forward U-shaped section and a rearward U-shaped section and hinge means connecting the forward and rearward sections together to allow the frame to more easily follow the pipeline. 19 Apparatus for excavating a ditch under a pipeline lying on the bottom of a body of water comprising, first and second U-shaped frame means for straddling the pipeline in tandem, hinge means connecting the first and second frame means for relative movement around a vertical axis to permit the frame means to more easily travel around curves in the pipeline, forwardly directed fluid jet means carried by the first frame means through which a fluid jet can be directed ahead of the frame means to excavate a ditch under the pipeline, and rearwardly directed fluid jet means through which a fluid jet can be directed rearwardly to provide a sufficient reactive force to move the frame means forwardly along the pipeline as the forwardly directed fluid jet means excavates the ditch under the pipeline.
 20. The apparatus of claim 19 further provided with means for directing a gas, such as air, into the ditch formed by the forwardly directed jet means to help clean the ditch for the pipeline. 